99 corolla 220000km/132000m have changed oil every 6000km. hearing a clacking noise when engine is cold . it gets louder as temperature drops below freezing and goes away after engine warms up. local mechanic suggests piston slap , a condition were cold metal differences between block and piston cause noise. no oil is burning , it is never down between changes , but it is annoying. any similiar info would be much appreciated.
